Mobile computing continues to grow quickly as mobile devices, such as smart phones, add more power and more features. Users of such devices may now access various services on the internet, such as mapping applications, electronic mail, text messaging, various telephone services, general web browsing, music and video viewing, and similar such services. The small size of mobile devices may make it difficult to interact with such services, because a full QWERTY keyboard may not be available on a mobile device or may not be available at all times. Thus, input to a mobile device may occur via a standard telephone dialing pad (e.g., via multi-tap inputs) or a touch screen.
In addition, interaction with a mobile device may occur in a variety of situations, in varying levels of concentration for a user. At one end of a spectrum, a user may be able to provide full attention to their device, such as when they are at their desk or riding on mass transit. At the other end of the spectrum, a user may be busy having a conversation or driving their automobile, so that any interaction with their mobile device should require a minimum level of attention from the user.